Journal of High Energy Physics

, 2012:9 | Cite as

Lorentz-violating vs. ghost gravitons: the example of Weyl gravity

  • Nathalie Deruelle
  • Misao Sasaki
  • Yuuiti SendoudaEmail author
  • Ahmed Youssef
Open Access


We show that the ghost degrees of freedom of Einstein gravity with a Weyl term can be tamed by a simple mechanism that invokes local Lorentz symmetry breaking. We demonstrate how the mechanism works in a cosmological setting. The presence of the Weyl term forces a redefinition of the quantum vacuum state of the tensor perturbations. As a consequence the amplitude of their spectrum blows up when the Lorentz-violating scale becomes comparable to the Hubble radius. Such a behaviour is in sharp contrast to what happens in standard Weyl gravity where the gravitational ghosts smoothly damp out the spectrum of primordial gravitational waves.


Cosmology of Theories beyond the SM Models of Quantum Gravity Classical Theories of Gravity 


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Copyright information

© SISSA 2012

Authors and Affiliations

  • Nathalie Deruelle
    • 1
  • Misao Sasaki
    • 2
  • Yuuiti Sendouda
    • 1
    • 2
    • 3
    Email author
  • Ahmed Youssef
    • 4
  1. 1.APC, CNRS-Université Paris 7Paris CEDEX 13France
  2. 2.Yukawa Institute for Theoretical PhysicsKyoto UniversityKyotoJapan
  3. 3.Graduate School of Science and TechnologyHirosaki UniversityHirosakiJapan
  4. 4.Institut für Mathematik und Institut für PhysikHumboldt-Universität zu BerlinBerlinGermany

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